In the manufacture of composite boards such as particle board, waferboard, and oriented strand board, layers and/or particles of wood and other materials are adhesively bonded and pressed together. The edges of such boards typically have either a flat profile, or a tongue-and-groove profile, depending upon the requirements of a particular application.
Composite boards of the type described above are commonly used in the fabrication of residential and commercial flooring and other applications where it is desirable to seal the edges and prevent the entry of moisture therein. Moisture intrusion into the board edges causes them to swell or warp over time, which, in flooring applications, can create uneveness and cracking cf floor coverings such as tile, linoleum and the like.
One method of sealing the edges of composite boards has been to spray a solvent, a water-based sealer, waxes or other sealing materials onto the edges of composite board to obtain the desired seal. One problem with the use of solvents is that they create environmental hazards due to evaporation during handling and/or application onto the composite board. In addition, overspraying or mis-spraying of sealing materials onto the edges of the board is a recurring problem with this method resulting in undesirable clean-ups, excess usage of material and rejects.
Another method of sealing the edges of composite boards involves the extrusion of a sealing material such as hot melt adhesive directly onto the board edge with an adhesive dispenser and a heated coating die. The coating die rests on the corners of the composite board, spanning the edge to be coated, so that the sealing material is spread over the entire surface area of the edge. While problems of overspray and/or mis-spraying are reduced with this method, the sealing material fails to penetrate into the edges of the board and can be relatively easily dislodged during shipment, handling and/or after a period of use of the board.